Method for detecting temperature and activity associated with a processor and using the results for controlling power dissipation associated with a processor

ABSTRACT

A method for detecting temperature and activity associated with a processor, results of the detecting being used for controlling power dissipation associated with the processor and/or apparatus and/or system employing the same.

This application is a Continuation of application Ser. No. 10/106,261,filed Mar. 26, 2002 now U.S. Pat. No. 6,901,524, which is a Divisionalof application Ser. No. 09/727,597 filed Dec. 1, 2000, now U.S. Pat. No.6,427,211, which is a Divisional of application Ser. No. 08/395,335filed Feb. 28, 1995, now U.S. Pat. No. 6,158,012, which is aContinuation-in-Part of application Ser. No. 08/023,831 filed Apr. 12,1993, now U.S. Pat. No. 6,006,336, which is a Continuation ofapplication Ser. No. 07/429,270 filed Oct. 30, 1989, now U.S. Pat. No.5,218,704.

BACKGROUND OF THF INVENTION

1. Field of the Invention

This invention relates to real-time computer thermal management andpower conservation, and more particularly to an apparatus and method fordecreasing and increasing central processing unit (CPU) clock rime basedon temperature and real-time activity levels within the CPU of aportable computer.

2. Description of the Related Art

During the development stages of personal computers, the transportableor portable computer has become very popular. Such portable computeruses a large power supply and really represents a small desktop personalcomputer. Portable computers are smaller and lighter than a desktoppersonal computer and allow a user to employ the same software that canbe used on a desktop computer.

The first generation “portable” computers only operated from an A/C wallpower. As personal computer development continued, battery-poweredcomputers were designed. Furthermore, real portability became possiblewith the development of new display technology, better disk storage, andlighter components. Unfortunately, the software developed was designedto run on desk top computers without regard to battery-powered portablecomputers that only had limited amounts of power available for shortperiods of time. No special considerations were made by the software,operating system (MS-DOS), Basic Input/Output System (BIOS), or thethird party application software to conserve power usage for theseportable computers.

As more and more highly functional software packages were developed,desktop computer users experienced increased performance from theintroductions of higher computational CPUs, increased memory, and fasterhigh performance disk drives. Unfortunately, portable computerscontinued to run only on A/C power or with large and heavy batteries. Intrying to keep up with the performance requirements of the desk topcomputers, and the new software, expensive components were used to cutthe power requirements. Even so, the heavy batteries still did not runvery long. This meant users of portable computers has to settle for A/Coperation or very short battery operation to have the performance thatwas expected from the third party software.

Portable computer designers stepped the performance down to 8088- and8086-type processors to reduce the power consumption. The supportingcircuits and CPU took less power to run and therefore, lighter batteriescould be used. Unfortunately, the new software requiring 80286-typeinstructions, that did not exist in the older slower 8088/8086 CPUs, didnot run. In an attempt to design a portable computer that could conservepower, thereby yielding longer battery operation, smaller units, andless weight, some portable computer designers proceeded to reduce powerconsumption of a portable computer while a user is not using thecomputer. For example, designers obtain a reduction in power usage byslowing or stopping the disk drive after some predetermined period ofinactivity; if the disk drive is not being used, the disk drive isturned off, or simply placed into a standby mode. When the user is readyto use the disk, the operator must wait until the disk drive spins upand the computer system is ready again for full performance before theoperator may proceed with the operation.

Other portable computer designers conserve power by turning the computerdisplay off when the keyboard is not being used. However, in normaloperation the computer is using full power. In other words, powerconservation by this method is practical only when the user is not usingthe components of the system. It is very likely, however, that the userwill turn the computer off when not in use. Nevertheless, substantialpower conservation while the operator is using the computer formeaningful work is needed. When the operator uses the computer, fulloperation of all components is required. During the intervals while theoperator is not using the computer, however, the computer could beturned off or slowed down to conserve power consumption. It is criticalto maintaining performance to determine when to slow the computer downor turn it off without disrupting the user's work, upsetting the thirdparty software, or confusing the operating system, until operation isneeded.

Furthermore, although a user can wait for the disk to spin up asdescribed above, application software packages cannot wait for the CPUto “spin up” and get ready. The CPU must be ready when the applicationprogram needs to compute. Switching to full operation must be completedquickly and without the application program being affected. Thisimmediate transition must be transparent to the user as well as to theapplication currently active. Delays cause user operational problems inresponse time and software compatibility, as well as general failure bythe computer to accurately execute a required program.

Other attempts at power conservation for portable computers includeproviding a “Shut Down” or “Standby Mode” of operation. The problem,again, is that the computer is not usable by the operator during thisperiod. The operator could just as well turned off the power switch ofthe unit to save power. This type of power conservation only allows theportable computer to “shut down” and thereby save power if the operatorforgets to turn off the power switch, or walks away from the computerfor the programmed length of time. The advantage of this type of powerconservation over just turning the power switch off/on is a much quickerreturn to full operation. However, this method of power conservation isstill not real-time, intelligent power conservation while the computeris on and processing data which does not disturb the operating system,BIOS, and any third party application programs currently running on thecomputer.

Some attempt to meet this need was made by VLSI vendors in providingcircuits that either turned off the clocks to the CPU when the user wasnot typing on the keyboard or woke up the computer on demand when akeystroke occurred. Either of these approaches reduce power but thecomputer is dead (unusable) during this period Background operationssuch as updating the system clock, communications, print spooling, andother like operations cannot be performed. Some existing portablecomputers employ these circuits. After a programmed period of noactivity, the computer turns itself off. The operator must turn themachine on again but does not have to reboot the operating system andapplication program. The advantage of this circuitry is like theexisting “shut down” operations, a quick return to full operationwithout restarting the computer. Nevertheless, this method only reducespower consumption when the user walks away from the machine and does notactually extend the operational like of the battery charge.

Thermal over-heating of CPUs and other related devices is anotherproblem vet to be addressed by portable computer manufacturers. CPUs aredesigned to operate within specific temperature ranges (varies dependingon CPU type, manufacturer, quality, etc). CPU performance and speeddegenerates when the limits of the operation temperature ranges areexceeded, especially the upper temperature range. This problem isparticularly acute with CPUs manufactured using CMOS technology wheretemperatures above the upper temperature range result in reduced CPUperformance and speed. Existing power saving techniques save power butdo not measure and intelligently control CPU and/or related devicetemperature.

SUMMARY OF THE INVENTION

In view of the above problems associated with the related art, it is anobject of the present invention to provide an apparatus and method forreal-time conservation of power and thermal management for computersystems without any real-time performance degradation, such conservationof power and thermal management remaining transparent to the user.

Another object of the present invention is to provide an apparatus andmethod for predicting CPU activity and temperature levels and using thepredictions for automatic power conservation and temperature control.

Yet another object of the present invention is to provide an apparatusand method which allows user modification of automatic activity andtemperature level predictions and using the modified predictions forautomatic power conservation and temperature control.

A further object of the present invention is to provide an apparatus andmethod for real-time reduction and restoration of clock speeds therebyreturning the CPU to full processing rate from a period of inactivitywhich is transparent to software programs.

These objects are accomplished in a preferred embodiment of the presentinvention by an apparatus and method which determine whether a CPU mayrest (including any PCI bus coupled to the CPU) based upon CPU activityand temperature levels and activates a hardware selector based upon thatdetermination. If the CPU may rest, or sleep, the hardware selectorapplies oscillations at a sleep clock level; if the CPU is to be active,the hardware selector applies oscillations at a high speed clock level.

The present invention examines the state of CPU activity andtemperature, as well as the activity of both the operator and anyapplication software currently active. This sampling of activity andtemperature is performed real-time, adjusting the performance level ofthe computer to manage power conservation, CPU temperature and computerpower. These adjustments are accomplished within the CPU cycles and dono affect the user's perception of performance.

Thus, when the operator for the third party software of the operatingsystem/BIOS is not using the computer, the present invention will effecta quick turn off or slow down of the CPU until needed, thereby reducingthe power consumption and CPU temperature, and will promptly restorefull CPU operation when needed without affecting perceived performance.This switching back into full operation from the “slow down” mode occurswithout the user having to request it and without any delay in theoperation of the computer while waiting for the computer to return to a“ready” state.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asother features and advantages thereof, will be best understood byreference to the detailed description with follows, read in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a flowchart depicting the self-tuning aspect of a preferredembodiment of the present invention.

FIGS. 2 a-2 d are flowcharts depicting the active power conservationmonitor employed by the present invention.

FIG. 3 is a simplified schematic diagram representing the active powerconservation associated hardware employed by the present invention.

FIG. 4 is a schematic of the sleep hardware for one embodiment of thepresent invention.

FIG. 5 is a schematic of the sleep hardware for another embodiment ofthe invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

If the period of computer activity in any given system is examined, theCPU and associated components have a utilization percentage. If the useris inputting data from the keyboard, the time between keystrokes is verylong in terms of CPU cycles. Many things can be accomplished by thecomputer during this time, such as printing a report. Even during theprinting of a report, time is still available for additional operationssuch as background updating of a clock/calendar display. Even so, thereis almost always spare time when the CPU is not being used. If thecomputer is turned off or slowed down during this spare time, then powerconsumption is obtained real-time. Such real-time power conservationextends battery operation life and lowers CPU temperature.

According to one embodiment of the present invention, to conserve powerand lower CPU temperature under MIS-DOS, as well as other operatingsystems such as OS/2, XENIS, and those for Apple computers, requires acombination of hardware and software. It should be noted that becausethe present invention will work in any system, while the implementationmay vary slightly on a system-by-system basis, the scope of the presentinvention should therefore not be limited to computer systems operatingunder IS/DOS.

Slowing down or stopping computer system components reduces powerconsumption and lowers CPU temperature, although the amount of powersaved and CPU temperature reduction may vary. Therefore, according tothe present invention, stopping the clock (where possible as some CPUscannot have their clocks stopped) reduces power consumption and CPUtemperature more than just slowing the clock.

In general, the number of operations (or instructions) per second may beconsidered to be roughly proportional to the processor clock:instructions/second=instructions/cycle*cycles/secondAssuming for simplicity that the same instruction is repeatedly executedso that instructions/second is constant, the relationship can beexpressed as follows:Fq=K ₁ *Clkwhere Fq is instructions/second, K₁ is constant equal to theinstructions/cycle, and Clk equals cycles/second. Thus, roughlyspeaking, the rate of execution increases with the frequency of the CPUclock.

The amount of power being used at any given moment is also related tothe frequency of the CPU clock and therefore to the rate of execution.In general this relationship can be expressed as follows:P=K ₂+(K ₃ *Clk)where P is power in watts, K₂ is a constant in watts, K₃ is a constantand expresses the number of wart-second/cycle, and Clk equals thecycles/second of the CPU clock. Thus it can also be said that the amountof power being consumed at any given time increases as the CPU clockfrequency increases.

Assume that a given time period T is divided into N intervals such thatthe power P is constant during each interval. Then the amount of energyE expended during T is given by:E=P(1) delta T ₁ +P(2) delta T ₂ . . . P(N) delta T _(N)Further assume that the CPU clock “CLK” has only two states, either “ON”or “OFF”. For the purposes of this discussion, the “ON” state representsthe CPU clock at its maximum frequency, while the “OFF” state representsthe minimum clock rate at which the CPU can operate (this may be zerofor CPUs that can have their clocks stopped). For the condition in whichthe CPU clock is always “ON”, each P(i) in the previous equation isequal and the total energy is:E(max)=P(on)*(delta T ₁+delta T₂ . . . delta T _(N))=P(on)*TThis represents the maximum power consumption of the computer in whichno power conservation measures are being used. If the CPU clock is “off”during a portion of the intervals, then there are two power levelspossible for each interval. The P(on) represents the power beingconsumed when the clock is in its “ON” state, while P(off) representsthe power being used when the clock is “OFF”. If all of the timeintervals in which the clock is “ON” are summed into the quantity“T(on)” and the “OFF” intervals are summed into “T(off)”, then itfollows:T=T(on)+T(off)Now the energy being used during period T can be written:E=[P(on)*T(on)]+[P(off)*T(off)]Under these conditions, the total energy consumed may be reduced byincreasing the time intervals T(off). Thus, by controlling the periodsof time the clock is in its “OFF” state, the amount of energy being usedmay be reduced. If the T(off) period is divided into a large number ofintervals during the period T, then as the width of each interval goesto zero, energy consumption is at a maximum. Conversely, as the width ofthe T(off) intervals increase, the energy consumed decreases.

If the “OFF” intervals are arranged to coincide with periods duringwhich the CPU is normally inactive, then the user cannot perceive anyreduction in performance and overall energy consumption is reduced fromthe E(max) state. In order to align the T(off) intervals with periods ofCPU inactivity, the CPU activity and temperature levels are used todetermine the width of the T(off) intervals in a closed loop. FIG. 1depicts such a closed loop. The activity level of the CPU is determinedat Step 10. If this level is a decrease over an immediately previousdetermination (Step 22), the present invention increases the T(off)interval (Step 30) and returns to determine the activity level of theCPU again. If, on the other hand, this activity level is an increaseover an immediately previous determination (Step 22), a determination ismade as to whether or not the temperature of the CPU is a concern (Step24). If CPU temperature is not a concern, the present inventiondecreases the T(off) interval (Step 20) and proceeds to again determinethe activity level of the CPU. If, on the other hand, CPU temperature isa concern, a determination is made as to whether or not the CPU isprocessing critical I/O, a critical function or a critical real-timeevent (Step 26). If critical I/O or critical function or a criticalreal-time event are being processed, the present invention decreases theT(off) interval (Step 20) and proceeds to again determine the activitylevel of the CPU. If no critical I/O is being processed, the presentinvention increases the T(off) interval (Step 20) and proceeds again todetermine the activity level of the CPU. Thus the T(off) intervals areconstantly being adjusted to match the system activity level and controlthe temperature level of the CPU.

Management of CPU temperature (thermal management) is necessary becauseCPUs are designed to operate within a specific temperature range. CPUperformance and speed deteriorates when the specified high operatingtemperature of a CPU is exceeded (especially in CMOS process CPUs wheretemperatures above the high operating temperature translate into slowerCPU speed). The heat output of a CPU is directly related to the powerconsumed by the CPU and heat it absorbs from devices and circuitry thatimmediately surround it. CPU power consumption increases with CPU clockspeed and the number of instructions per second to be performed by theCPU. As a result, heat related problems are becoming more common asfaster and increasingly complex CPUs are introduced and incorporatedinto electronic devices.

In any operating system, two key logic points exist: an IDLE, or “donothing”, loop within the operating system and an operating systemrequest channel, usually available for services needed by theapplication software. By placing logic inline with these logic points,the type of activity request made by an application software can beevaluated, power conservation and thermal management can be activatedand slice periods determined. A slice period is the number of T(on) vs.T(off) intervals over time, computed by the CPU activity and thermallevels. An assumption may be made to determine CPU activity level:Software programs that need service usually need additional services andthe period of time between service requests can be used to determine theactivity level of any application software running on the computer andto provide slice counts for power conservation according to the presentinvention. Another assumption that may be made is that each CPU has atemperature coefficient unique to that CPU-CPU temperature rise time,CPU maximum operating temperature, CPU temperature fall time andintervention time required for thermal control. If this information isnot provided by the CPU manufacturer, testing of the CPU being used (oranother of the same make and type tested under similar conditions) isrequired to obtain accurate information.

Once the CPU is interrupted during a power conservation and thermalmanagement slice (T(off)), the CPU will save the interrupted routine'sstate prior to vectoring to the interrupt software. Off course, sincethe power conservation and thermal management software was operatingduring this slice, control will be returned to the active powerconservation and thermal management loop (monitor 40) which simplymonitors the CPU's clock to determine an exit condition for the powerconservation and thermal management mode thereby exiting from T(off) toT(on) state. The interval of the next power conservation and thermalmanagement state is adjusted by the activity level monitor, as discussedabove in connection with FIG. 1. Some implementations can create anautomatic exit from T(off) by the hardware logic, thereby forcing thepower conservation and thermal management loop to be exitedautomatically and executing an interval T(on).

More specifically, looking now at FIGS. 2 a-2 d, which depict the activepower conservation and thermal management monitor 40 of the presentinvention. The CPU installs monitor 40 either via a program stored inthe CPU ROM or loads it from an external device storing the program inRAM. Once the CPU has loaded monitor 40, it continues to INIT 50 forsystem interrupt initialization, user configurational setup, andsystem/application specific initialization. IDLE branch 60 (morespecifically set out in FIG. 2 b) is executed by a hardware or softwareinterrupt for an IDLE or “do nothing” function. This type of interruptis caused by the CPU entering either an IDLE or a “do nothing” loop(i.e., planned inactivity). The ACTIVITY branch 70 of the flow chart,more fully described below in relation to FIG. 2 d, is executed by asoftware or hardware interrupt due to an operating system or I/O servicerequest, by an application program or internal operating systemfunction. An I/O service request made by a program may, for example, bea disk 110, read, print, load, etc. Regardless of the branch selected,control is eventually returned to the CPU operating system at RETURN 80.The INIT branch 50 of this flowchart, shown in FIG. 2 a, is executedonly once if it is loaded via program into ROM or is executed every timeduring power up if it is loaded from an external device and stored inthe RAM. Once this branch of active power and thermal management monitor40 has been fully executed, whenever control is yielded from theoperating system to the power conservation and thermal management mode,either IDLE 60 or ACTIVITY 70 branches are selected depending on thetype of CPU activity: IDLE branch 60 for power conservation and thermalmanagement during planned inactivity and ACTIVITY branch 70 for powerconservation and thermal management during CPU activity.

Looking more closely at INIT branch 50, after all system interrupt andvariables are initialized, the routine continues at Step 90 to set thePower_level equal to DEFAULT_LEVEL. In operating systems where the userhas input control for the Power_level, the program at Step 100 checks tosee if a User_level has been selected. If the User_level is less thanzero or greater than the MAXIMUM_LEVEL, the system used theDEFAULT_LEVEL. Otherwise, it continues onto Step 110 where it modifiesthe Power_level to equal the User_level.

According to the preferred embodiment of the present invention, thesystem at Step 120 sets the variable Idle_tick to zero and the variableActivity_tick to zero. Under an MS/DOS implementation. Idle_tick refersto the number of interrupts found in a “do nothing” loop. Activity_tickrefers to the number of interrupts caused by an activity interrupt whichin turn determines the CPU activity level. Tick count represents a deltatime for the next interrupt. Idle_tick is a constant delta time from onetick to another (interrupt) unless overwritten by a software interrupt.A software interrupt may reprogram delta time between interrupts.

After setting the variables to zero, the routine continues on to Setup130 at which time any application specific configuration fine-tuning ishandled in terms of system-specific details and the system isinitialized. Next the routine arms the interrupt I/O (Step 140) withinstructions to the hardware indicating the hardware can take control atthe next interrupt. INIT branch 50 then exits to the operating system,or whatever called the active power and thermal management monitororiginally, at RETURN 80.

Consider now IDLE branch 60 of active power and thermal managementmonitor 40, more fully described at FIG. 2 b. In response to a plannedinactivity of the CPU, monitor 40 (not specifically shown in thisFigure) checks to see if entry into IDLE branch 60 is permitted by firstdetermining whether the activity interrupt is currently busy. If Busy_Aequals BUSY_FLAG (Step 150), which is a reentry flag, the CPU is busyand cannot now be put to sleep. Therefore, monitor 40 immediatelyproceeds to RETURN I 160 and exits the routine. RETURN I 160 is anindirect vector to the previous operating system IDLE vector interruptfor normal processing stored before entering monitor 40. (I.e., thiscauses an interrupt return to the last chained vector.)

If the Busy_A interrupt flag is not busy, then monitor 40 checks to seeif the Busy Idle interrupt flag, Busy_I, equals BUSY_FLAG (Step 170). Ifso, this indicates the system is already in IDLE branch 60 of monitor 40and therefore the system should not interrupt itself. IfBusy_I=BUSY_FLAG, the system exits the routine at RETURN_I indirectvector 160.

If, however, neither the Busy_A reentry flag or the Busy_I reentry flaghave been set, the routine sets the Busy_I flag at Step 180 for reentryprotection (Busy_I=BUSY_FLAG). At Step 190 Idle_tick is incremented byone. Idle_tick is the number of T(on) before a T(off) interval and isdetermined from IDLE interrupts, setup interrupts and from CPU activityand temperature levels. Idle_tick increments by one to allow forsmoothing of events, thereby letting a critical I/O activity controlsmoothing.

At Step 200 monitor 40 checks to see if Idle_tick equals IDLE_MAXTICKS.IDLE_MAXTICKS is one of the constants initialized in Setup 130 of INITbranch 50, remains constant for a system, and is responsible forself-tuning of the activity and thermal levels. If Idle_tick does notequal IDLE_MAXTICKS, the Busy_J flag is cleared at Step 210 and exitsthe loop proceeding to the RETURN I indirect vector 160. If, however,Idle_tick equals IDLE_MAXTICKS, Idle_tick is set equal to IDLESTART_TICKS (Step 220). IDLE_START_TICKS is a constant which may or maynot be zero (depending on whether the particular CPU can have its clockstopped). This step determines the self-tuning of how often the rest ofthe sleep functions may be performed. By setting IDLE_START_TICKS equalto IDLE_MAXTICKS minus one, a continuous T(off) interval is achieved. AtStep 230, the Power_level is checked. If it is equal to zero, themonitor clears the Busy_I flag (Step 210), exits the routine at RETURN I160, and returns control to the operating system so it may continue whatit was originally doing before it entered active power monitor 40.

If, however, the Power_level does not equal zero at Step 240, theroutine determines whether an interrupt mask is in place. An interruptmask is set by the system/application software, and determines whetherinterrupts are available to monitor 40. If interrupts are NOT_AVAILABLE,the Busy_I reentry flag is cleared and control is returned to theoperating system to continue what it was doing before it entered monitor40. Operating systems, as well as application software, can set T(on)interval to yield a continuous T(on) state by setting the interrupt maskequal to NOT_AVAILABLE.

Assuming an interrupt is AVAILABLE, monitor 40 proceeds to the SAVEPOWER subroutine 250 which is fully executed during one T(off) periodestablished by the hardware state. (For example, in the preferredembodiment of the present invention, the longest possible interval couldbe 18 ms, which is the longest time between two ticks or interrupts fromthe real-time clock.) During the SAVE POWER subroutine 250, the CPUclock is stepped down to a sleep clock level.

Once a critical I/O operation forces the T(on) intervals, the IDLEbranch 60 interrupt tends to remain ready for additional critical I/Orequests. As the CPU becomes busy with critical I/O, less T(off)intervals are available. Conversely, as critical I/O requests decrease,and the time intervals between them increase, more T(off) intervals areavailable. IDLE branch 60 is a self-tuning system based on feedback fromCPU activity and temperature interrupts and tends to provide more T(off)intervals as the activity level slows as long as CPU temperature is nota concern. As soon as monitor 40 has completed SAVE POWER subroutine250, shown in FIG. 2 c and more fully described below, the Busy_Ireentry flag is cleared (Step 210) and control is returned at RETURN I160 to whatever operating system originally requested monitor 40.

Consider now FIG. 2 c, which is a flowchart depicting the SAVE POWERsubroutine 250. Monitor 40 determines what the I/O hardware high speedclock is at Step 260. It sets the CURRENT_CLOCK RATE equal to therelevant high speed clock and saves this value to be used for CPUs withmultiple level high speed clocks. Thus, if a particular CPU has 12 MHzand 6 MHz high speed clocks, monitor 40 must determine which high speedclock the CPU is at before monitor 40 reduces power so it mayreestablish the CPU at the proper high speed clock when the CPU awakens.At Step 270, the Save_clock_rate is set equal to the CURRENT_CLOCK_RATEdetermined. Save_clock_rate 270 is not used when there is only one highspeed clock for the CPU. Monitor 40 now continues to SLEEPCLOCK 280,where a pulse is sent to the hardware selector (shown in FIG. 3) to putthe CPU clock to sleep (i.e., lower or stop its clock frequency). TheI/O port hardware sleep clock is at much lower oscillations than the CPUclock normally employed.

At this point either of two events can happen. A system/applicationinterrupt may occur or a real-time clock interrupt may occur. If asystem/application interrupt 290 occurs, monitor 40 proceeds tointerrupt routine 300, processing the interrupt as soon as possible,arming interrupt I/O at Step 310, and returning to determine whetherthere has been an interrupt (Step 320). Since in this case there hasbeen an interrupt, the Save_clock_rate is used (Step 330) to determinewhich high speed clock to return the CPU to and SAVE POWER subroutine250 is exited at RETURN 340. If, however, a system/application interruptis not received, the SAVE POWER subroutine 250 will continue to waituntil a real-time clock interrupt has occurred (Step 320). Once such aninterrupt has occurred, SAVE POWER subroutine 250 will continue to waituntil a real-time clock interrupt has occurred (Step 320). Once such aninterrupt has occurred, SAVEPOWER subroutine 250 will execute interruptloop 320 several times. If however, control is passed when the sleepclock rate was zero, in other words, there was no clock, the SAVE POWERsubroutine 250 will execute interrupt loop 320 once before returning theCPU clock to the Save_clock_rate 330 and exiting (Step (340)).

Consider now FIG. 2 d which is a flowchart showing ACTIVITY branch 70triggered by an application/system activity request via an operatingsystem service request interrupt. ACTIVITY branch 70 begins with reentryprotection. Monitor 40 determines at Step 350 whether Busy_I has beenset to BUSY_FLAG. If it has, this means the system is already inACTIVITY branch 70 and cannot be interrupted. If Busy_I=BUSY_FLAG,monitor 40 exits to RETURN I 160, which is an indirect vector to an oldactivity vector interrupt for normal processing, via an interrupt vectorafter the operating system performs the requested service.

If however, the Busy_I flag does not equal BUSY_FLAG, which meansACTIVITY branch 70 is not being accessed, monitor 40 determines at Step360 if the BUSY_A flag has been set equal to BUSY_FLAG. If so, controlwill be returned to the system at this point because ACTIVITY branch 70is already being used and cannot be interrupted. If the Busy_A flag hasnot been set, in other words, Busy_A does not equal BUSY_FLAG, monitor40 sets Busy_A equal to BUSY_FLAG at Step 370 so as not to beinterrupted during execution of ACTIVITY branch 70. At Step 380 thePower_level is determined. If Power_level equals zero, monitor 40 exitsACTIVITY branch 70 after clearing the Busy_A reentry flag (Step 390). Ifhowever, the Power_level does not equal zero, the CURRENT_CLOCK_RATE ofthe I/O hardware is next determined. As was true with Step 270 of FIG.2C, Step 400 of FIG. 2 d uses the CURRENT_CLOCK_RATE if there aremultiple level high speed clocks for a given CPU. Otherwise,CURRENT_CLOCK_RATE always equals the CPU high speed clock. After theCURRENT_CLOCK_RATE is determined (step 400), at Step 410 Idle_tick isset equal to the constant START_TICKS established for the previouslydetermined CURRENT_CLOCK_RATE. T(off) intervals are established based onthe current high speed clock that is active.

Monitor 40 next determines that a request has been made. A request is aninput by the application software running on the computer, for aparticular type of service needed. At Step 420, monitor 40 determineswhether the request is a CRITICAL I/O. If the request is a CRITICAL I/O,it will continuously force T(on) to lengthen until the T(on) is greaterthan the T(off), and monitor 40 will exit ACTIVITY branch 70 afterclearing the Busy_A reentry flag (Step 390). If, on the other hand, therequest is not a CRITICAL I/O, then the Activity_tick is incremented byone at Step 430. It is then determined at Step 440 whether theActivity_tick now equals ACTIVITY_MAXTICKS. Step 440 allows a smoothingfrom a CRITICAL I/O, and makes the system ready from another CRITICALI/O during Activity_tick T(on) intervals. Assuming Activity_tick doesnot equal ACTIVITY_MAXTICKS, ACTIVITY branch 70 is exited after clearingthe Busy_A reentry flag (Step 390). If, on the other hand, theActivity_tick equals constant ACTIVITY_MAXTICKS, at Step 450Activity_tick is set to the constant LEVEL_MAXTICKS established for theparticular Power_level determined at Step 380.

Now monitor 40 determines whether an interrupt mask exists (Step 460).An interrupt mask is set by system/application software. Setting it toNOT_AVAILABLE creates a continuous T(on) state. If the interrupt maskequals NOT_AVAILABLE, there are no interrupts available at this time andmonitor 40 exits ACTIVITY branch 70 after clearing the Busy_A reentryflag (Step 390). If, however, an interrupt is AVAILABLE, monitor 40determines at Step 470 whether the request identified at Step 420 wasfor a SLOW I/O_INTERRUPT. Slow I/O requests may have a delay until theI/O device becomes “ready”. During the “make ready” operation, acontinuous T(off) interval may be set up and executed to conserve power.Thus, if the request is not a SLOW I/O_INTERRUPT, ACTIVITY branch 70 isexited after clearing the Busy_A reentry flag (Step 390). If, however,the request is a SLOW I/O_INTERRUPT, and time yet exists before the I/Odevice becomes “ready”, monitor 40 then determines at Step 480 whetherthe I/O request is COMPLETE (i.e., is I/O device ready?). If the I/Odevice is not ready, monitor 40 forces T(off) to lengthen, therebyforcing the CPU to wait, or sleep, until the SLOW I/O device is ready.At this point it has time to save power and ACTIVITY branch 70 entersSAVE POWER subroutine 250 previously described in connection with toFIG. 2C. If, however, the I/O request is COMPLETE, control is returnedto the operating system subsequently to monitor 40 exiting ACTIVITYbranch 70 after clearing Busy_A reentry flag (Step 390).

Self-tuning is inherent within the control system of continuous feedbackloops. The software of the present invention can detect when CPUactivity is low and/or CPU temperature is high enough to be of concernand therefore when the power conservation and thermal management aspectof the present invention may be activated. To detect when CPUtemperature is high enough to be of concern, the power and thermalmanagement software monitors a thermistor on the PWB board adjacent theCPU (or mounted directly on or in the CPU if the CPU includes athermistor). In one embodiment of the present invention, the softwaremonitors the thermistor 18 times/sec through an A/D converter. If nopower is being conserved and the temperature of the thermistor is withinacceptable parameters, then monitoring continues at the same rate. If,however, the temperature of the thermistor is rising, a semaphore is setto tell the system to start watching CPU temperature for possiblethermal management action. Each CPU has a temperature coefficient uniqueto that specific CPU. Information on how long it takes to raise thetemperature and at what point intervention must occur to preventperformance degradation must be derived from information supplied withthe CPU or through testing.

According to one embodiment of the invention, a counter is set inhardware to give an ad hoc interrupt (counter is based on coefficient oftemperature rise). The thermal management system must know how long ittakes CPU temperature to go down to minimize temperature effect. If thecounter is counting down and receives an active power interrupt, the adhoc interrupt is turned off because control has been regained throughthe active power and thermal management. The result is unperceivedoperational power savings. The ad hoc interrupt can be overridden ormodified by the active power interrupt which checks the type gradienti.e., up or down, checks the count and can adjust the up count and downcount ad hoc operation based on what the CPU is doing real time. Ifthere are no real time interrupts, then the timer interval continuallycomes in and monitors the gradual rise in temperature and it will adjustthe ad hoc counter as it needs it up or down. The result is dynamicfeedback from the active power and thermal management into the ad hoctimer, adjusting it to the dynamic adjustment based on what thetemperature rise or fall is at any given time and how long it takes forthat temperature to fall off or rise through the danger point. This is adifferent concept that just throwing a timer out ad hoc and letting itrun.

For example, assume that the CPU being used has a maximum safe operatingtemperature of 95 degrees C. (obtained from the CPU spec sheet or fromactual testing). Assume also that a thermistor is located adjacent theCPU and that when the CPU case is at 95 degrees C., the temperature ofthe thermistor may be lower since it is spaced a distance from the CPU(such as 57 degrees C.). A determination should be made as to how longit took the CPU to reach 95 degrees. If it took an hour, the system maydecide to sample the thermistor every 45 minutes. Once the CPU is at 95degrees, CPU temperature may need to be sampled every minute to makesure the temperature is going down, otherwise, the temperature might goup, i.e., to 96 degrees. If 5 minutes are required to raise CPUtemperature from 45 to 96 degrees, CPU temperature sampling must be at aperiod less than 5 minutes—i.e., ever; 3 or 1 minutes. If thetemperature is not going down, then the length of the rest cycles shouldbe increased. Continual evaluation of the thermal read constant is keyto knowing when CPU temperature is becoming a problem, when thermalmanagement intervention is appropriate and how much time can be allowedfor other things in the system. This decision must be made before thetarget temperature is reached. Once CPU temperature starts to lower, itis, O.K. to go back to the regular thermal constant number because 1)you have selected the right slice period, or 2) the active power portionof the active power and thermal management has taken over, so thesampling rate can be reduced.

Examples of source code that can be stored in the CPU ROM or in anexternal RAM device, according to one embodiment of the invention, arelisted in the COMPUTER PROGRAMS LISTING section under: 1) Interrupt 8Timer interrupt service—listed on pages ______ to ______; 2) CPU SleepRoutine—listed on pages ______ to ______; 3) FILE=FORCE5.ASM—listed onpages ______ to ______; and 4) FILE=Thermal.EQU—listed on pages ______to ______.

Utilizing the above listed source code, and assuming that Interrupt 8Timer interrupt service is the interrupt mask called at Step 240 of IDLEloop 60 or at Step 460 of ACTIVITY loop 70, the procedure for thermalmanagement is set up “Do Thermal Management if needed” after which thesystem must decide if there is time for thermal management “Time forThermal Management?”. If there is time for thermal management, thesystem calls the file “force_sleep” if there is time to sleep (whichalso sleeps any device receiving the same clock signal and which deviceis coupled to a PCI bus coupled to the CPU), or alternatively, could doa STI nop and a halt—which is an alternate way and does not get PCIdevices and does not have a feedback loop from the power and temperaturemanagement systems. The “force_sleep” file gets feedback from otherpower systems. Force_sleep does a jump to force5.asm, which is the PCImultiple sleep program. Are there speakers busy in the system? Is theresomething else in the system going on from a power management point ofview? Are DMAs running in the system? Sleeping may not be desirableduring a sound cycle. It needs to know what is going on in the system todo an intelligent sleep. The thermal management cares about the CPU andcares about all the other devices out there because collectively theyall generate heat.

There are some equations in the program that are running—others that mayor may not be running. “tk” is the number of interrupts per second thatare sampled times the interval that is sampled over. “it” represents athermal read constant and the thermal read constant in the presentembodiment is 5. In the code, the thermal read constant is dynamicallyadjusted later depending on what the temperature is. Thus, this is thestarting thermal read interval, but as the temperature rises, readingshould be more often and the cooler it is, reading should be less oftenthan 5 minutes—e.g., 10 minutes. The thermal read constant will adjust.TP1 or TP2 represents what percentage of the CPU cycles we want tosample at—for example, TP7 set at 50 the number of interrupts that haveto occur over some period of time such that if we take that number thatgoing to represent every so many clock cycles that go by before wesample and sleep the CPU. These equations are variable. Other equationscan also be used.

Thus, one concept of the present invention is that there are variouslevels of temperature that require testing in relationship to thehottest point to be managed. The sample period will change dependingupon temperature and active feedback. Active feedback may be requiredeven though thermal management has determined that the CPU temperatureis too high and should be reduced (by slowing or stopping the CPUclock). CPU clock speed may not be reduced because other system thingsare happening—the result is intelligent feedback. The power conservationand thermal management systems asks the CPU questions such as are youdoing something now that I cannot go do? If not, please sleep. If yes,don't sleep and come back to me so that I can reset my count. The resultis a graduated effect up and graduated effect down and the thermal readconstant time period adjusts itself in response to CPU temperature.Performance taken away from the user during power conservation andthermal management control is balanced against critical I/O going on inthe system.

Thermal management cooperates with active power management so that whenactive power management gets a chance to take over the active feedbackcan start degrading even though the temperature has not. Existingthermal management systems turn on and stay on until the temperaturegoes down. Unfortunately, this preempts things in the system. Such isnot the case in the environment of the present invention. The same sleepmanager works in conjunction with power conservation and thermalmanagement—the sleep manager has global control. As a example, while CPUtemperature may be rising or have risen to a level of concern, thesystem may be processing critical I/O, such as a wave file being played.With critical I/O, the system of the present invention will play thewave file without interruption even though the result may be a higherCPU temperature. CPUs do not typically overheat all at once. There is atemperature rise gradient. The system of the present invention takesadvantage of the temperature rise gradient to give a user things thataffect the user time slices and take it away from him when its notaffected.

Thermal management can be also be achieved using a prediction mode.Prediction mode utilizes no sensors or thermistors or even knowledge asto actual CPU temperature. Prediction mode uses a guess—i.e. that thesystem will need the ad hoc interrupt once every 5 seconds or 50times/second (=constant) and then can take it up or down based on whatthe system is doing with the active power and thermal management. Theprediction theory can also be combined with actual CPU temperaturemonitoring.

Once the power conservation and thermal management monitor is activated,a prompt return to full speed CPU clock operation within the interval isachieved so as to not degrade the performance of the computer. Toachieve this prompt return to full speed CPU clock operation, thepreferred embodiment of the present invention employs some associatedhardware.

Looking now at FIG. 3 which shows a simplified schematic diagramrepresenting the associated hardware employed by the present inventionfor active power conservation and thermal management. When monitor 40(not shown) determines the CPU is ready to sleep, it writes to an I/Oport (not shown) which causes a pulse on the SLEEP line. The rising edgeof this pulse on the SLEEP line causes flip flop 500 to clock a high toQ and a low to Q_. This causes the AND/OR logic (AND gates 510, 520, ORgate 530) to select the pulses travelling the SLEEP CLOCK line fromSLEEP CLOCK oscillator 540 to be sent to and used by the CPU CLOCK.SLEEP CLOCK oscillator 540 is a slower clock than the CPU clock usedduring normal CPU-activity. The high coming from the Q of flip flop 500ANDed (510) with the pulses coming from SLEEP CLOCK oscillator 540 isORed (530) with the result of the low on the Q_of flip flop 500 ANDed(520) with the pulse generated along the HIGH SPEED CLOCK line by theHIGH SPEED CLOCK oscillator 550 to yield the CPU CLOCK. When the I/Oport designates SLEEP CLOCK, the CPU CLOCK is then equal to the SLEEPCLOCK oscillator 540 value. If, on the other hand, an interrupt occurs,an interrupt—value clears flip flop 500, thereby forcing the AND/ORselector (comprising 510, 520 and 530) to choose the HIGH SPEED CLOCKvalue, and returns the CPU CLOCK value to the value coming from HIGHSPEED CLOCK oscillator 550. Therefore, during any power conservationand/or thermal management operation on the CPU, the detection of anyinterrupt within the system will restore the CPU operation at full clockrate prior to vectoring and processing the interrupt.

It should be noted that the associated hardware needed, external to eachof the CPUs for any given system, may be different based on theoperating system used, whether the CPU can be stopped, etc.Nevertheless, the scope of the present invention should not be limitedby possible system specific modifications needed to permit the presentinvention to actively conserve power and manage CPU temperature in thenumerous available portable computer systems. For example two actualimplementations are shown in FIGS. 4 and 5, discussed below.

Many VSLI designs today allow for clock switching of the CPU speed. Thelogic to switch from a null clock or slow clock to a fast clock logic isthe same as that which allows the user to chance speeds by a keyboardcommand. The added logic of monitor 40 working with such switchinglogic, causes an immediate return to a fast clock upon detection of anyinterrupt. This simple logic is the key to the necessary hardwaresupport to interrupt the CPU and thereby allow the processing of theinterrupt at full speed.

The method to reduce power consumption under MS-DOS employs the MS-DOSIDLE loop trap to gain access to the “do nothing” loop. The IDLE loopprovides special access to application software and operating systemoperations that are in a state of IDLE of low activity. Careful examination is required to determine the activity level at any given pointwithin the system. Feedback loops are used from the interrupt 21Hservice request to determine the activity level. The prediction ofactivity level is determined by interrupt 21H requests, from which thepresent invention thereby sets the slice periods for “sleeping” (slowingdown or stopping) the CPU. An additional feature allows the user tomodify the slice depending on the activity level of interrupt 21H. Themethod to produce power conservation under WINDOWS employs real andprotect modes to save the power interrupt which is called by theoperating system each time WINDOWS has nothing to do.

Looking now at FIG. 4, which depicts a schematic of an actual sleephardware implementation for a system such as the Intel 80386 (CPU cannothave its clock stopped). Address enable bus 600 and address bus 610provide CPU input to demultiplexer 620. The output of demultiplexer 620is sent along SLEEPCS—and provided as input to OR gates 630, 640. Theother inputs to OR gates 630, 640 are the I/O write control line and theI/O read control line, respectively. The outputs of these gates, inaddition to NOR gate 650, are applied to D flip flop 660 to decode theport. “INTR” is the interrupt input from the I/O port (peripherals) intoNOR gate 650, which causes the logic hardware to switch back to the highspeed clock. The output of flip flop 660 is then fed, along with theoutput from OR gate 630, to tristate buffer 670 to enable it to readback what is on the port. A1 of the above-identified hardware is used bythe read/write 110 port (peripherals) to select the power saving “Sleep”operation. The output “SLOW_” is equivalent to “SLEEP” in FIG. 2, and isinputted to flip flop 680, discussed later.

The output of SLEEP CLOCK oscillator 690 is divided into two slowerclocks by D flip flops 700, 710. In the particular implementation shownin FIG. 4, 16 MHz sleep clock oscillator 690 is divided into 4 MHz and 8MHz clocks. Jumper J1 selects which clock is to be the “SLEEP CLOCK”.

In his particular implementation, high speed clock oscillator 720 is a32 MHz oscillator, although this particular speed is not a requirementof the present invention. The 32 MHz oscillator is put in series with aresistor (for the implementation shown, 33 ohms), which is in serieswith two parallel capacitors (10 pF). The result of such oscillations istied to the clocks of D flip flops 730, 740.

D flip flops 680, 730, 740 are synchronizing flip flops; 680, 730 werenot shown in the simplified sleep hardware of FIG. 2. These flip flopsare used to ensure the clock switch occurs only on clock edge. As can beseen in FIG. 4, as with flip flop 500 of FIG. 2, the output of flip flop740 either activates OR gate 750 or OR gate 760, depending upon whetherthe CPU is to sleep (“FASTEN_”) or awaken (“SLOWEN_”).

OR gates 750, 760 and AND gate 770 are the functional equivalents to theAND/OR selector of FIG. 2. They are responsible for selecting either the“slowclk” (slow clock, also known as SLEEP CLOCK) or high speed clock(designated as 32 MHz on the incoming line). In this implementation, theSlow clock is either 4 MHz or 8 MHz, depending upon jumper J1, and thehigh speed clock is 32 MHz. The output of AND gate 770 (ATUCLK)establishes the rate of the CPU clock, and is the equivalent of CPUCLOCK of FIG. 2. (If the device includes a PCI bus, the output of ANDgate 770 may also be coupled to the PCI bus if it is to utilize theclock signal.)

Consider now FIG. 5, which depicts a schematic of another actual sleephardware implementation for a system such as the Intel 30286 (CPU canhave its clock stopped). The Western Digital FE3600 VLSI is used for thespeed switching with a special external PAL 780 to control the interruptgating which wakes up the CPU on any interrupt. The software powerconservation according to the present invention monitors the interruptacceptance, activating the next P(i)deltaTi interval after theinterrupt.

Any interrupt request to the CPU will return the system to normaloperation. An interrupt request (“INTRQ”) to the CPU will cause the PALto issue a Wake Up signal on the RESCPU line to the FE3001 (not shown)which in turn enables the CPU and the DMA clocks to bring the systemback to its normal state. This is the equivalent of the “INterrupt_” ofFIG. 2. Interrupt Request is synchronized to avoid confusing the statemachine so that Interrupt (INT-DET) will only be detected while thecycle is active. The rising edge of RESCPU will wake up the FE 3001which in turn releases the whole system from the Sleep Mode.

Implementation for the 386SX is different only in the external hardwareand software power conservation loop. The software loop will setexternal hardware to switch to the high speed clock on interrupt priorto vectoring the interrupt. Once return is made to the powerconservation software, the high speed clock cycle will be detected andthe hardware will be reset for full clock operation.

Implementation for OS/2 uses the “do nothing” loop programmed as aTHREAD running in background operation with low priority. Once theTHREAD is activated, the CPU sleep, or low speed clock, operation willbe activated until an interrupt occurs thereby placing the CPU back tothe original clock rate.

Although interrupts have been employed to wake up the CPU in thepreferred embodiment of the present invention, it should be realizedthat any periodic activity within the system, or applied to the system,could also be used for the same function.

While several implementations of the preferred embodiment of theinvention has been shown and described, various modifications andalternate embodiments will occur to those skilled in the art.Accordingly, it is intended that the invention be limited only in termsof the appended claims.

COMPUTER PROGRAMS LISTING

-   1) Interrupt 8 Timer interrupt service—pages 27 to 32. Interrupt 8    Timer interrupt service is loaded onto the CPU ROM or an external    RAM and is an interrupt mask that may be called at Step 240 of IDLE    loop 60 or at Step 460 of ACTIVITY loop 70.-   2) CPU Sleep Routine—page 33. CPU Sleep Routine is loaded onto the    CPU ROM or an external RAM and is a file that may be called at Step    250 of IDLE loop 60 or ACTIVITY loop 70.-   3) FILE=FORCE5.ASM—pages 34 to 38. FILE=FORCES.ASM is a PCI multiple    sleep program that is loaded onto the CPU ROM or an external RAM and    is a file that may be called at Step 250 of IDLE loop 60 or ACTIVITY    loop 70.-   4) FILE=Thermal.EQU—listed on page 39. FILE=Thermal.EQU is loaded    onto the CPU ROM or an external RAM and is a file that may be called    at STEP 240 of IDLE loop 60 or at Step 460 of ACTIVITY loop 70.

1. A method, comprising the steps of: detecting temperature and activityassociated with a processor; comparing an amount of detected activitywith an amount of detected activity from a previous detecting ofactivity associated with said processor and said temperature with areference temperature; and using results of said comparing for reducingpower consumption associated with said processor if said amount ofdetected activity is an increase over an amount of detected activityfrom a previous determination and said temperature is at and/or abovesaid reference temperature.
 2. The method of claim 1, wherein an amountof said reducing power consumption is proportional to the differencebetween said amount of detected activity and said amount of detectedactivity from a previous determination.
 3. The method of claim 1,wherein said reduction in power consumption is accomplished inincremental steps.
 4. The method of claim 1, wherein said reduction inpower consumption continues until no change is detected between saidamount of detected activity and said amount of detected activity from aprevious determination.
 5. The method of claim 1, wherein said reducingpower consumption continues until one of: a) no change is detectedbetween said amount of detected activity and said amount of detectedactivity from a previous determination; b) said processor has reachedits minimum power consumption level; and c) said temperature is atand/or above a reference temperature.
 6. The method of claim 1, whereinsaid power consumption is accomplished by lowering a clock frequency. 7.The method of claim 6, wherein said clock frequency is lowered inincremental steps.
 8. The method of claim 1, wherein said powerconsumption is accomplished by lowering a clock speed.
 9. The method ofclaim 8, wherein said clock speed is lowered in incremental steps. 10.The method of claim 1, wherein said reduction in power consumption isaccomplished while said processor is processing data.
 11. The method ofclaim 10, wherein said data is part of a program being run on saidprocessor.
 12. A method, comprising the steps of: detecting temperatureand activity associated with a processor; comparing an amount ofdetected activity with an amount of detected activity from a previousdetecting of activity associated with said processor and saidtemperature with a reference temperature; and using results of saidcomparing for increasing power consumption associated with saidprocessor if said amount of detected activity is an increase over anamount of detected activity from a previous determination and saidtemperature is below said reference temperature.
 13. The method of claim12, wherein an amount of said increasing power consumption isproportional to the difference between said amount of detected activityand said amount of detected activity from a previous determination. 14.The method of claim 12, wherein said increase in power consumption isaccomplished in incremental steps.
 15. The method of claim 12, whereinsaid increase in power consumption continues until no change is detectedbetween said amount of detected activity and said amount of detectedactivity from a previous determination.
 16. The method of claim 13,wherein said increasing power consumption continues until one of: a) nochange is detected between said amount of detected activity and saidamount of detected activity from a previous determination; b) saidprocessor has reached its maximum power consumption level; and c) saidtemperature is below a reference temperature.
 17. The method of claim12, wherein said power consumption is accomplished by raising a clockfrequency.
 18. The method of claim 17, wherein said clock frequency israised in incremental steps.
 19. The method of claim 12, wherein saidpower consumption is accomplished by raising a clock speed.
 20. Themethod of claim 19, wherein said clock speed is raised in incrementalsteps.
 21. The method of claim 12, wherein said increase in powerconsumption is accomplished while said processor is processing data. 22.The method of claim 21, wherein said data is part of a program being runon said processor.
 23. A method, comprising the steps of: detectingtemperature and activity associated with a processor; comparing anamount of detected activity with an amount of detected activity from aprevious detecting of activity associated with said processor and saidtemperature with a reference temperature; and using results of saidcomparing for reducing power consumption associated with said processorif said amount of detected activity is a decrease over an amount ofdetected activity from a previous determination and/or said temperatureis at and/or above a reference temperature and increasing powerconsumption associated with said processor if said amount of detectedactivity is an increase over an amount of detected activity from aprevious determination and/or said temperature is below the referencetemperature.
 24. A method, comprising the steps of: detectingtemperature and activity associated with a processor; comparing anamount of detected activity with another amount of activity andcomparing said detected temperature with another temperature; and usingresults of said detecting and comparing for reducing power consumptionassociated with said processor if said amount of detected activity is adecrease over said another amount of activity and said temperature is atand/or above said another temperature.
 25. A method, comprising thesteps of: detecting temperature and activity associated with aprocessor; comparing an amount of detected activity with another amountof activity and comparing said detected temperature with anothertemperature; and using results of said comparing for increasing powerconsumption associated with said processor if said amount of detectedactivity is an increase over said another amount of activity and saiddetected temperature is below said another temperature.
 26. A method,comprising the steps of: detecting temperature and activity associatedwith a processor; comparing an amount of detected activity with anotheramount of activity and comparing said detected temperature with anothertemperature; and using results of said comparing for reducing powerconsumption associated with said processor if said amount of detectedactivity is a decrease over said another amount of activity and/or saiddetected temperature is at and/or above said another temperature andincreasing power consumption associated with said processor if saidamount of detected activity is an increase over said another amount ofactivity and/or said detected temperature is below said anothertemperature.